Multifunctional hydrogen liquefaction performance test platform and method

Abstract

The invention provides a multifunctional hydrogen liquefaction performance test platform and method, and relates to the technical field of hydrogen liquefaction, and the multifunctional hydrogen liquefaction performance test platform comprises a gas supply system, a catalytic reaction and gradient cooling system and a rewarming and measuring system which are connected in sequence. The catalytic reaction and gradient cooling system comprises a first-stage cooling and conversion unit, a second-stage cooling and conversion unit and a third-stage cooling and conversion unit, wherein the first-stage cooling and conversion unit is used for pre-cooling hydrogen by using a liquid nitrogen cold source and carrying out primary ortho-para hydrogen conversion reaction in a first-stage ortho-para hydrogen catalytic conversion reactor; and the second-stage cooling, liquefying and converting unit is used for receiving the hydrogen from the first-stage cooling and converting unit, deeply cooling and liquefying the hydrogen by using a cold source provided by a GM refrigerator, and meanwhile, carrying out secondary ortho-para hydrogen conversion reaction in a second-stage ortho-para hydrogen catalytic conversion reactor. According to the invention, the problems of high consumption and low performance of a hydrogen liquefaction process are effectively solved, and a synergistic influence mechanism of coupling an ortho-parahydrogen catalyst loading mode with flow heat exchange in a wide-temperature-range multi-conversion mode is disclosed.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen liquefaction, and in particular to a multifunctional hydrogen liquefaction performance testing platform and method. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] As a clean and efficient energy carrier, hydrogen has broad application prospects. Compared with traditional hydrogen energy storage and transportation technologies, cryogenic liquid hydrogen storage has the advantage of high mass storage density. However, the traditional hydrogen liquefaction process has three major bottlenecks: (1) Hydrogen liquefaction is accompanied by the conversion of normal and para-hydrogen and heat release. The released heat causes the liquid hydrogen to vaporize, which limits the production capacity of liquid hydrogen. (2) Catalysts play an important role in the hydrogen liquefaction process, accelerating the conversion of normal and para-hydrogen and improving the liquefaction efficiency. However, the research on catalyst loading methods in the existing technology mainly focuses on packed catalysts and wall-mounted catalysts. Packed catalysts have problems such as poor fluidity and low catalyst utilization, while wall-mounted catalysts have a small loading capacity and a low catalyst loading per unit volume, which limits the catalytic performance. (3) The current conversion methods of para-hydrogen mainly include isothermal conversion, adiabatic conversion and continuous conversion. Different conversion methods have their own advantages and limitations. Isothermal conversion is suitable for scenarios that require simple operation, but its economic cost is relatively high; adiabatic conversion provides greater flexibility, but the problem of heat management needs to be solved to avoid affecting equipment performance; continuous conversion performs well in terms of energy efficiency. At present, most of the research on the continuous conversion of para-hydrogen in the hydrogen liquefaction process remains in numerical simulation research. There is no complete experimental data to reveal the multi-mode conversion of para-hydrogen coupled with wide temperature range flow heat transfer mechanism under different catalyst loading methods in microchannels. The research on the continuous conversion mechanism of para-hydrogen and the flow heat transfer performance in microchannels is still at the theoretical level. There is a lack of integrated research on the conversion of para-hydrogen coupled with flow heat transfer under different catalyst loading methods, different temperature zones and different conversion modes. Summary of the Invention

[0004] To address the above problems, the present invention provides a multifunctional hydrogen liquefaction performance testing platform and method, which effectively solves the problems of high consumption and low performance in the hydrogen liquefaction process, and reveals the synergistic influence mechanism of the coupling flow heat exchange of the normal and para-hydrogen catalyst loading mode in a wide temperature range and multi-conversion mode.

[0005] To solve the technical problems raised in the background technology, the first aspect of the present invention provides a multifunctional hydrogen liquefaction performance testing platform, comprising: Gas supply system: used to provide and purify raw hydrogen; Catalytic reaction and gradient cooling system: used to receive hydrogen from the gas supply system, perform catalytic conversion of normal and para hydrogen, and perform graded cooling and liquefaction of the hydrogen, including: Primary cooling and conversion unit: The hydrogen is pre-cooled using a liquid nitrogen cooling source, and the first para-hydrogen conversion reaction is carried out in the primary para-hydrogen catalytic conversion reactor; Secondary cooling, liquefaction and conversion unit: used to receive hydrogen from the primary cooling and conversion unit, deeply cool the hydrogen to liquefaction using the cold source provided by the GM refrigerator, and simultaneously carry out secondary normal-para-hydrogen conversion reaction in the secondary normal-para-hydrogen catalytic conversion reactor; Rewarming and measurement system: Receives hydrogen gas / liquid hydrogen flow from the secondary cooling liquefaction and conversion unit, including: Rewarming unit: used to rewarm low-temperature hydrogen; Data measurement unit: used to measure temperature, pressure, flow rate and parahydrogen content parameters during the hydrogen liquefaction process.

[0006] Furthermore, the test platform also includes: The catalyst loading system comprises a detachable conversion microchannel (12), wherein the conversion microchannel (12) is arranged inside the first-stage normal-parahydrogen catalytic conversion reactor and the second-stage normal-parahydrogen catalytic conversion reactor, and is used to load a filled normal-parahydrogen conversion catalyst (25) or a wall-mounted normal-parahydrogen conversion catalyst (26); The first-stage normal-parahydrogen catalytic conversion reactor and the second-stage normal-parahydrogen catalytic conversion reactor adopt a detachable isothermal conversion reactor (11), an adiabatic conversion reactor (24) or a continuous conversion reactor (14).

[0007] Furthermore, in the catalyst loading system: The filled normal-parahydrogen conversion catalyst (25) is filled in the inner space of the conversion microchannel (12); The wall-supported normal-parahydrogen conversion catalyst (26) is supported on the inner wall surface of the conversion microchannel (12).

[0008] Furthermore, the secondary cooling liquefaction and conversion unit includes a liquid hydrogen dewar (16) with a double-layer cold preservation structure, wherein the double-layer cold preservation structure consists of an inner liquid nitrogen cold shield structure and an outer vacuum sandwich structure, and is used to store liquid hydrogen and reduce heat leakage.

[0009] Furthermore, the secondary cooling liquefaction and conversion unit also includes a reflux heat exchanger (13) located at the inlet of the liquid hydrogen dewar (16), which is used for heat exchange between the incoming hydrogen and the outgoing low-temperature hydrogen / liquid hydrogen.

[0010] Furthermore, the test platform also includes: Control system: used to connect and regulate valves and pressures in the gas supply system, catalytic reaction and cooling system, rewarming and measurement system; The control system comprises a regulating valve (4), a pressure reducing valve (20) and a venting pipeline; the pressure reducing valve (20) is arranged on the hydrogen final outlet pipeline for reducing the hydrogen pressure; a flow meter (21) and a regulating valve (4) are provided on the venting pipeline; the flow meter (21) is connected to the pressure reducing valve (20).

[0011] Furthermore, the gas supply system comprises a hydrogen gas cylinder (3), a helium gas cylinder (2) and a molecular sieve container (5); the hydrogen gas cylinder (3) and the helium gas cylinder (2) are connected to the molecular sieve container (5), and a regulating valve (4) is provided at the outlet of each of the hydrogen gas cylinder (3) and the helium gas cylinder (2).

[0012] Furthermore, the primary cooling and conversion unit comprises a liquid nitrogen dewar (8) containing liquid nitrogen (10) and a precooling pipeline (9); the precooling pipeline (9) is immersed in the liquid nitrogen (10), constituting a primary cooling place for hydrogen; the primary normal-parahydrogen catalytic conversion reactor is arranged downstream of the primary cooling place or integrated therein.

[0013] Furthermore, in the secondary cooling liquefaction and conversion unit, the continuous conversion reactor (14) is in direct thermal contact with the cold head of the GM refrigerator (15).

[0014] A second aspect of the present invention provides a testing method using the multifunctional hydrogen liquefaction performance testing platform, comprising: S1: Loading the activated normal-parahydrogen conversion catalyst into the conversion microchannel (12), selecting a wall-loaded or filled-type loading structure; S2: selecting any one or more types of normal-parahydrogen catalytic conversion reactors from an isothermal conversion reactor (11), an adiabatic conversion reactor (24), and a continuous conversion reactor (14), and placing the catalytic conversion reactor at a selected position of the gradient cooling system; S3: hydrogen is introduced, and primary cooling and conversion, secondary cooling, liquefaction and conversion are performed in sequence; S4: Record and analyze the temperature, pressure, flow rate and parahydrogen content parameters during the hydrogen liquefaction process based on the data measurement unit; S5: changing at least one of the catalyst loading method, the reactor type, or the reactor position, and repeating steps S3-S4.

[0015] Compared with the existing technology, the multifunctional hydrogen liquefaction performance testing platform and method provided by the present invention have the following beneficial effects: (1) To solve the technical problems of poor fluidity of packed catalysts and small loading of wall-mounted catalysts in the background art, the present invention provides a packed / wall-mounted dual-mode structure through a detachable conversion channel design to solve the problem. The catalyst loading system provided by the present invention adopts a detachable conversion microchannel (12) to support the rapid replacement of packed (25) or wall-mounted (26) catalysts. A direct comparison of the performance differences between the two loading methods is achieved. At the same time, through flexible switching, the catalyst utilization rate is optimized, the reaction kinetics of each temperature zone are matched, and the conversion efficiency of normal and para hydrogen is significantly improved.

[0016] (2) To solve the technical problems of the separation of isothermal / adiabatic / continuous conversion mode research and the lack of wide temperature range experimental data in the background technology, the catalytic reaction system provided by the present invention adopts detachable isothermal (11), adiabatic (24), and continuous conversion reactors (14), and supports flexible deployment in a gradient cooling system. Specifically, the isothermal conversion reactor (11) is immersed in liquid nitrogen (10) to study the intrinsic activity of the catalyst at a constant low temperature; the continuous conversion reactor (14) is in direct thermal contact with the GM refrigerator cold head (15) to achieve simultaneous liquefaction and conversion, revealing the gas-liquid two-phase heat and mass transfer coupling mechanism in the liquid phase temperature zone; at the same time, the reactor position is adjustable to support multi-temperature zone graded conversion experiments, filling the gap in wide temperature range multi-mode coupling research.

[0017] (3) To solve the problem of hydrogen liquefaction releasing heat and causing liquid hydrogen to vaporize in the background technology, the present invention provides a liquid hydrogen dewar with a double-layer cold-insulation structure. Specifically, the liquid hydrogen dewar (16) adopts a double-layer structure of an inner liquid nitrogen cold shield + an outer vacuum interlayer (22), and is combined with a vacuum pump (17) to maintain a high vacuum degree. The inner liquid nitrogen cold shield shields radiant heat, and the outer vacuum interlayer suppresses gas heat transfer, reducing system heat leakage, significantly reducing cooling loss, and ensuring experimental stability in the deep cold zone (liquid hydrogen temperature zone).

[0018] (4) To solve the problems of unreasonable cooling capacity distribution and missing performance data in traditional processes, the present invention provides hardware structures such as a reflux heat exchanger, a multi-node sensor, a reheating pipe (18), and a heating resistor (19) to solve the problem. Specifically, the secondary cooling unit is provided with a reflux heat exchanger (13) to exchange heat between the inlet hydrogen and the outflowing low-temperature hydrogen / liquid hydrogen, recovering more than 85% of the liquid hydrogen cooling capacity and reducing the energy consumption of the GM refrigerator; the data measurement unit deploys temperature / pressure sensors (6, 7) and a gas chromatograph (23) at multiple nodes such as the liquid nitrogen dewar (8), the liquid hydrogen dewar (16), and the reactor outlet to synchronously obtain temperature, pressure, and parahydrogen content data to support the establishment of a gas-liquid two-phase flow-heat transfer-reaction coupling model in the microchannel; the reheating unit reheats the exhausted hydrogen through the heating resistor (19); avoids safety hazards caused by low-temperature hydrogen, and ensures the measurement accuracy of the flow meter (21).

[0019] (5) The present invention addresses the issues of impurity contamination of the catalyst and high-pressure risks through purge design and pressure reduction control. Specifically, the gas supply system uses a helium cylinder (2) to purge the pipeline, and the molecular sieve container (5) purifies the hydrogen to prevent water vapor from freezing and blocking the microchannel, thereby improving the catalyst activity stability by more than 30%. The control system is equipped with a pressure reducing valve (20) and a venting pipeline; the outlet hydrogen pressure is reduced to a safe range (less than 0.5 MPa) to avoid high-pressure damage to the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which constitute a part of the present disclosure, are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation to the present disclosure.

[0021] Figure 1 A schematic diagram of the connection structure of the multifunctional hydrogen liquefaction performance testing platform provided in Example 1 of the present invention; Figure 2 A schematic diagram of the connection structure of the n-parahydrogen catalytic conversion reactor of the multifunctional hydrogen liquefaction performance testing platform provided in Example 1 of the present invention; Figure 3 Schematic diagram of the catalytic loading structure of the normal-para hydrogen conversion of the multifunctional hydrogen liquefaction performance testing platform provided in Example 1 of the present invention.

[0022] In the figure: 1. Liquid nitrogen tank; 2. Helium cylinder; 3. Hydrogen cylinder; 4. Regulating valve; 5. Molecular sieve container; 6. Pressure sensor; 7. Temperature sensor; 8. Liquid nitrogen Dewar; 9. Precooling pipeline; 10. Liquid nitrogen; 11. Isothermal conversion reactor; 12. Conversion microchannel; 13. Reflux heat exchanger; 14. Continuous conversion reactor; 15. GM refrigerator; 16. Liquid hydrogen Dewar; 17. Vacuum pump; 18. Reheating pipe; 19. Heating resistor; 20. Pressure reducing valve; 21. Flow meter; 22. Vacuum interlayer; 23. Gas chromatograph; 24. Adiabatic conversion reactor; 25. Filled para-hydrogen conversion catalyst; 26. Wall-mounted para-hydrogen conversion catalyst. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0024] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0025] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0026] All data in this embodiment is obtained in compliance with laws and regulations and based on the consent of the user, and is used legally.

[0027] To study the hydrogen liquefaction process in microchannels with different catalyst loading methods, further reveal and improve the flow and heat exchange mechanism of microchannels with different catalyst loading methods coupled with continuous heat release, clarify the synergistic influence mechanism of the continuous conversion of normal-parahydrogen and the liquefaction process, and effectively solve the high consumption and low performance problems of traditional hydrogen liquefaction processes, the following examples provide a hydrogen liquefaction performance test platform based on the loading method of normal-parahydrogen conversion catalyst in microchannels and a method for coupling normal-parahydrogen staged conversion with hydrogen gradient cooling. This realizes the construction of a hydrogen liquefaction performance test platform for a microchannel loaded with normal-parahydrogen conversion catalyst coupled with continuous normal-parahydrogen conversion, and can study the hydrogen liquefaction behavior based on the synergistic influence of continuous normal-parahydrogen conversion in different temperature zones and the catalyst loading method in the microchannel.

[0028] Example 1 like Figure 1 The present invention provides a multifunctional hydrogen liquefaction performance testing platform, comprising: Gas supply system: used to provide and purify raw hydrogen; Catalytic reaction and gradient cooling system: used to receive hydrogen from the gas supply system, perform catalytic conversion of normal and para hydrogen, and perform graded cooling and liquefaction of the hydrogen, including: Primary cooling and conversion unit: The hydrogen is pre-cooled using a liquid nitrogen cooling source, and the first para-hydrogen conversion reaction is carried out in the primary para-hydrogen catalytic conversion reactor; Secondary cooling, liquefaction and conversion unit: used to receive hydrogen from the primary cooling and conversion unit, deeply cool the hydrogen to liquefaction using the cold source provided by the GM refrigerator, and simultaneously carry out secondary normal-para-hydrogen conversion reaction in the secondary normal-para-hydrogen catalytic conversion reactor; Rewarming and measurement system: Receives hydrogen gas / liquid hydrogen flow from the secondary cooling liquefaction and conversion unit, including: Rewarming unit: used to rewarm low-temperature hydrogen; Data measurement unit: used to measure temperature, pressure, flow rate and parahydrogen content parameters during the hydrogen liquefaction process.

[0029] The overall architecture of the test platform provided by the present invention solves the technical problems of high energy consumption, low efficiency, and lack of multi-temperature zone and multi-mode integrated testing capabilities in traditional processes, realizes multi-stage cooling-conversion-liquefaction integrated testing, and provides complete data support for process optimization.

[0030] Among them, in the continuous conversion mode, the catalytic reaction system and the gradient cooling system work together to realize the continuous conversion of normal and para hydrogen in different temperature zones and the hydrogen liquefaction process with integrated flow heat exchange.

[0031] Specifically, the gas supply system includes a hydrogen cylinder (3), a helium cylinder (2), and a molecular sieve container (5); the hydrogen cylinder (3) and the helium cylinder (2) are connected to the molecular sieve container (5), and a regulating valve (4) is provided at the outlet. The molecular sieve container (5) in the gas supply system purifies the hydrogen to prevent water vapor from freezing and clogging the microchannel, thereby extending the life of the catalyst; the gradient cooling system adopts a graded cooling design (liquid nitrogen pre-cooling + GM deep cooling), which reduces the liquefaction energy consumption compared to traditional single-stage cooling.

[0032] In a specific embodiment, the gas supply system includes a helium cylinder (2), a hydrogen cylinder (3) and a regulating valve (4). The helium cylinder (2) and the hydrogen cylinder (3) are connected through the same pipeline. Before injecting hydrogen, the regulating valve (4) of the helium cylinder (2) is opened to purge the experimental system to remove impurities such as air and water vapor in the experimental system. After the purge is completed, the regulating valve (4) of the helium cylinder (2) is closed, and the regulating valve (4) of the hydrogen cylinder (3) is opened to inject hydrogen. The helium cylinder (2) is used to purge the experimental system to remove impurities including air and water vapor in the pre-cooling microchannel and the liquefaction microchannel.

[0033] The gas supply system ensures the purity of the raw hydrogen, effectively preventing impurities (such as water vapor) from freezing and clogging the microchannels or contaminating the catalyst, ensuring the accuracy of experimental results and stable system operation. The shared pipeline and independent regulating valve design simplifies the system structure and facilitates operation and switching.

[0034] Specifically, the test platform also includes: The catalyst loading system comprises a detachable conversion microchannel (12), the conversion microchannel (12) being arranged inside the first-stage normal-parahydrogen catalytic conversion reactor and the second-stage normal-parahydrogen catalytic conversion reactor, and being used to load a filled normal-parahydrogen conversion catalyst (25) or a wall-mounted normal-parahydrogen conversion catalyst (26); like Figure 2 The first-stage normal-parahydrogen catalytic conversion reactor and the second-stage normal-parahydrogen catalytic conversion reactor adopt a detachable isothermal conversion reactor (11), an adiabatic conversion reactor (24) or a continuous conversion reactor (14).

[0035] The catalyst loading system provided by the present invention solves the technical problems of poor fluidity of filled catalysts, small loading capacity of wall-mounted catalysts, and fragmented conversion model research through detachable conversion microchannels and switchable reactor types. It realizes rapid switching between filled and wall-mounted types and direct performance comparison. At the same time, it can flexibly deploy multiple conversion modes, filling the gap in wide temperature range experiments.

[0036] like Figure 3 , in the catalyst loading system: The filled normal-parahydrogen conversion catalyst (25) is filled in the inner space of the conversion microchannel (12); The wall-supported normal-parahydrogen conversion catalyst (26) is supported on the inner wall surface of the conversion microchannel (12).

[0037] The above loading method solves the technical problems of low catalyst utilization and limited catalytic performance. The adaptive adjustment of the loading method can match the reaction kinetics of each temperature zone to optimize the catalyst utilization.

[0038] Specifically, the secondary cooling liquefaction and conversion unit includes a liquid hydrogen dewar (16) with a double-layer cold insulation structure. The double-layer cold insulation structure consists of an inner liquid nitrogen cold shield structure and an outer vacuum sandwich structure, which is used to store liquid hydrogen and reduce heat leakage. The double-layer cold insulation structure solves the technical problem of limited production capacity caused by liquid hydrogen vaporization, reduces heat leakage, and ensures the stability of experiments in the deep cold zone.

[0039] Specifically, the secondary cooling liquefaction and conversion unit further includes a reflux heat exchanger (13) located at the inlet of the liquid hydrogen dewar (16), which is used for heat exchange between the incoming hydrogen and the outgoing low-temperature hydrogen / liquid hydrogen.

[0040] The heat exchange between the inlet hydrogen and the outflowing liquid hydrogen in the reflux heat exchanger (13) solves the technical problem of unreasonable cooling capacity distribution, recovers more than 85% of the liquid hydrogen cooling capacity, and reduces the energy consumption of the GM refrigerator.

[0041] Specifically, the primary cooling and conversion unit includes a liquid nitrogen dewar (8) containing liquid nitrogen (10) and a precooling pipeline (9); the precooling pipeline (9) is immersed in the liquid nitrogen (10), constituting a primary cooling place for hydrogen; and the primary normal-parahydrogen catalytic conversion reactor is arranged downstream of the primary cooling place or integrated therein.

[0042] The liquid nitrogen dewar (8) + pre-cooling pipeline (9) immersed in liquid nitrogen (10) solves the technical problem of high energy consumption of single-stage cooling, realizes a graded cooling design, and reduces the total energy consumption of liquefaction.

[0043] Specifically, in the two-stage cooling liquefaction and conversion unit, the continuous conversion reactor (14) is in direct thermal contact with the cold head of the GM refrigerator (15). This solves the technical problem of the unclear conversion-flow-heat transfer coupling mechanism in the liquid phase temperature zone, achieves synchronous liquefaction and conversion, and reveals the gas-liquid two-phase heat and mass transfer mechanism.

[0044] In a specific embodiment, the catalyst loading system includes: a conversion microchannel (12), a filled ortho-parahydrogen conversion catalyst (25) and a wall-mounted ortho-parahydrogen conversion catalyst (26). The conversion microchannel (12) is a catalyst loading site. In this embodiment, the ortho-parahydrogen conversion catalyst is Fe(OH)3. The filled catalyst (25) is filled inside the catalytic conversion channel, and the wall-mounted catalyst (26) is loaded onto the inner wall of the catalytic conversion channel to achieve catalytic conversion of ortho-parahydrogen.

[0045] The catalyst loading system provides two typical catalyst loading methods (filled and wall-mounted) for comparative studies. Filled loading allows for high loading capacity but also high flow resistance and potentially limited heat transfer. Wall-mounted loading, on the other hand, provides a large contact area with the fluid, lower pressure drop, and higher heat transfer efficiency. The interchangeable microchannel design enables direct comparison of the effects of different loading methods (filled vs. wall-mounted) on n-parahydrogen conversion efficiency, system pressure drop, heat transfer performance, and ultimately liquefaction efficiency, providing key experimental data for optimizing catalyst loading strategies.

[0046] The catalytic reaction system includes: a para-hydrogen catalytic conversion reactor, which is the place where the para-hydrogen conversion occurs and is respectively placed at the primary cooling position and the secondary cooling position to realize the graded conversion of para-hydrogen in multiple temperature zones. The para-hydrogen catalytic conversion reactor includes an isothermal conversion reactor (11), an adiabatic conversion reactor (24) and a continuous conversion reactor (14). The isothermal conversion reactor (11) is placed at the cold source position to maintain isothermal conditions, the adiabatic conversion reactor (24) is independently arranged outside the cold source, and the continuous conversion reactor (14) is placed in the raw hydrogen channel.

[0047] The catalytic reaction system offers three conversion modes (isothermal, adiabatic, and continuous) and supports flexible deployment at different locations (different temperature zones) within the system. Isothermal conversion facilitates the study of intrinsic catalyst activity at a constant low temperature; adiabatic conversion facilitates the study of conversion heat effects and temperature rise; and continuous conversion simulates the actual liquefaction process, performing conversion during cooling / liquefaction. The multi-temperature zone and multi-mode switchable design enables comprehensive investigation of the kinetic behavior of normal-parahydrogen conversion and its coupling with flow and heat transfer under different operating conditions (especially during wide-temperature gradient cooling), filling the gap in existing technologies for multi-mode coupled experimental research.

[0048] The gradient cooling system includes: a liquid nitrogen dewar (8), a liquid nitrogen tank (1), liquid nitrogen (10), a pre-cooling pipeline (9), a liquid hydrogen dewar (16), a vacuum pump (17), a GM refrigerator (15), a continuous conversion reactor (14) and a reflux heat exchanger (13). The liquid nitrogen dewar (8) is provided with a liquid nitrogen replenishment port and a nitrogen venting port. The inlet and outlet pipelines of the liquid nitrogen dewar (8) are provided with a temperature sensor (7) and a pressure sensor (6); the outlet pipeline of the liquid hydrogen dewar (16) is provided with a temperature sensor (7). The improved liquid hydrogen dewar structure adds a two-layer cold insulation system of liquid nitrogen cold screen and vacuum interlayer to reduce heat leakage of the system, and realizes the construction of a multifunctional hydrogen liquefaction performance test platform with multi-temperature zone and multi-conversion mode based on the loading mode of normal-para-hydrogen conversion catalyst. It can study the normal-para-hydrogen conversion, heat exchange and liquefaction-integration synergistic mechanism of the hydrogen liquefaction process under multifunctional matching switching, thereby optimizing the working efficiency of the hydrogen liquefaction process.

[0049] The liquid nitrogen tank (1) is used to replenish the liquid nitrogen (10) for the liquid nitrogen dewar (8), and the liquid nitrogen (10) provides a cold source for the first-stage cooling of hydrogen. The precooling pipeline (9) is a place for the first-stage cooling of hydrogen. The liquid hydrogen dewar (16) is a vacuum chamber with a two-layer cold-insulation structure. In this embodiment, the inner layer of the two-layer cold-insulation structure is a liquid nitrogen (10) sandwich structure to reduce the radiation heat exchange inside the dewar, and the outer layer is a vacuum sandwich (22) structure to reduce the heat exchange between the liquid nitrogen and the outside. The vacuum pump (17) is connected to the liquid hydrogen dewar (16). The GM refrigerator (15) provides a cold source for the second-stage cooling (liquefaction) of hydrogen. The continuous conversion reactor is attached to the cold head of the GM refrigerator (15), which can realize the simultaneous catalytic conversion and liquefaction of normal and para-hydrogen. The reflux heat exchanger is a place for heat exchange between the inlet hydrogen of the low-temperature liquefaction system and the low-temperature hydrogen after liquefaction.

[0050] The unique dual-layer cold insulation design of an inner liquid nitrogen cold shield and an outer vacuum interlayer, provided by this invention, significantly reduces heat leakage from the liquid hydrogen dewar. The liquid nitrogen cold shield effectively shields the internal cryogenic zone (liquid hydrogen) from the effects of thermal radiation from the external environment, while the vacuum interlayer minimizes heat transfer by gas conduction and convection. This significantly improves the system's thermal insulation performance, reduces the cooling capacity required to maintain low temperatures, ensures efficient secondary cooling (liquefaction) and a stable low-temperature environment, and creates the necessary conditions for accurately measuring the conversion of normal and para-hydrogen and flow heat transfer performance in the liquid hydrogen temperature range. By directly integrating the continuous conversion reactor with the GM refrigerator cold head, the catalytic conversion of normal and para-hydrogen is carried out simultaneously at the critical location where hydrogen liquefaction occurs (the cryogenic zone). This integrated design enables realistic simulation and study of the complex coupling mechanisms between catalyst activity, conversion reaction kinetics, and intense heat exchange and phase change processes at low temperatures during the actual liquefaction process (in the gas-liquid two-phase region or the liquid phase), which is difficult to achieve with existing technologies.

[0051] Specifically, the test platform also includes: Control system: used to connect and regulate valves and pressures in the gas supply system, catalytic reaction and cooling system, rewarming and measurement system; The control system includes a regulating valve (4), a pressure reducing valve (20) and a venting pipeline; the pressure reducing valve (20) is arranged on the hydrogen final outlet pipeline for reducing the hydrogen pressure; a flow meter (21) and a regulating valve (4) are provided on the venting pipeline; the flow meter (21) is connected to the pressure reducing valve (20).

[0052] The regulating valve (4) and the pressure reducing valve (20) in the control system are designed for the high-pressure risk of the test platform. The pressure reducing valve (20) can reduce the hydrogen pressure in the pipeline to avoid damage to experimental instruments and equipment under high pressure.

[0053] The flow and pressure of each branch are precisely controlled by regulating valves, and the pressure reducing valve ensures that the system operates at a safe pressure, ensuring the controllability and safety of the experimental process and providing a means to study the performance under different pressure conditions.

[0054] Specifically, the reheating unit includes a reheating pipe (18) and a heating resistor (19). The reheating pipe (18) is connected to the hydrogen outflow pipeline. The heating resistor (19) is used to heat the low-temperature hydrogen flowing through the reheating pipe (18), reheat the low-temperature hydrogen, prevent the low-temperature hydrogen from entering the atmosphere, and reduce safety hazards.

[0055] After the experiment is completed, the low-temperature hydrogen is warmed to close to ambient temperature before being discharged. This effectively prevents the safety hazards that may be caused by the direct discharge of low-temperature hydrogen (such as material brittle cracking, air condensation leading to suffocation or explosion risks), and prevents low-temperature hydrogen from damaging measuring equipment such as flow meters, ensuring measurement accuracy.

[0056] Specifically, the data measurement unit includes: Temperature sensors (7) and pressure sensors (6) are arranged at multiple key node pipelines of the platform; A flow meter (21) is provided on the hydrogen final outlet pipeline; A gas chromatograph (23) is connected to the outlet pipelines of the primary cooling and conversion unit and the secondary cooling, liquefaction and conversion unit to measure the parahydrogen content in the hydrogen.

[0057] A regulating valve (4) is provided on the inlet pipeline of the gas chromatograph (23).

[0058] The core of this invention lies in a comprehensive, high-precision data measurement unit. Multi-point temperature and pressure sensors monitor the status of key system locations in real time; flow meters record flow changes; and a gas chromatograph directly and quantitatively measures the core indicator—parahydrogen content. This rich, synchronized data provides a comprehensive foundation for in-depth analysis of the degree of parahydrogen conversion (conversion rate), system pressure drop (hydraulic performance), heat exchange efficiency (thermal performance), and ultimate liquefaction performance under different catalyst loading methods, conversion modes, and temperature ranges, supporting mechanistic research and model validation.

[0059] Example 2 The present invention provides a method for testing the performance of multifunctional hydrogen liquefaction, using the multifunctional hydrogen liquefaction performance testing platform provided in Example 1, comprising the following steps: S1: Loading the activated normal-parahydrogen conversion catalyst into the conversion microchannel (12), selecting a wall-loaded or filled-type loading structure; S2: selecting any one or more types of normal-parahydrogen catalytic conversion reactors from an isothermal conversion reactor (11), an adiabatic conversion reactor (24), and a continuous conversion reactor (14), and placing the catalytic conversion reactor at a selected position of the gradient cooling system; S3: hydrogen is introduced, and primary cooling and conversion, secondary cooling, liquefaction and conversion are performed in sequence; S4: Record and analyze the temperature, pressure, flow rate and parahydrogen content parameters during the hydrogen liquefaction process based on the data measurement unit; S5: Change at least one of the catalyst loading method, reactor type, or reactor position, and repeat steps S3-S4.

[0060] The inventive concept of repeating the test after changing the load mode / reactor type / position provided by the above-mentioned test method solves the technical problem of the lack of multivariable collaborative experimental data in the prior art, realizes flexible combination testing, and establishes a flow-heat transfer-reaction coupling model.

[0061] Specifically, the testing method provided in this embodiment includes the following steps: Step 1: Load the wall-mounted normal-parahydrogen conversion catalyst (26) particles after high-temperature activation onto the wall surface of the conversion microchannel (12), and place the microchannel (12) with the wall-mounted catalyst into the isothermal conversion reactor (11) and the continuous conversion reactor (14).

[0062] Step 2: Place the isothermal conversion reactor (11) in liquid nitrogen (10) to maintain isothermal conditions, and place the continuous conversion reactor (14) in contact with the GM refrigerator cold head (15) to ensure that hydrogen liquefaction and normal-parahydrogen conversion proceed simultaneously.

[0063] Step 3: Turn on the vacuum pump (17) to ensure that the liquid hydrogen dewar (16) is in a vacuum state.

[0064] Step 4: Purge the experimental system with the helium cylinder (2) to remove impurities including air and water vapor in the system pipeline.

[0065] Step 5: After the purge is completed, a stable flow of hydrogen is injected into the experimental system through the hydrogen cylinder (3). The raw hydrogen is purified through the molecular sieve container (5). The pressure and temperature are measured by the pressure sensor (6) and the temperature sensor (7) before entering the pre-cooling pipeline (9).

[0066] Step 6: The cold source of the pre-cooling pipeline (9) is provided by the liquid nitrogen (10) in the liquid nitrogen dewar (8), wherein the liquid nitrogen (10) in the liquid nitrogen dewar (8) is replenished by the liquid nitrogen tank (1). The hydrogen is cooled in the pre-cooling pipeline (9) and then enters the isothermal conversion reactor (11) to perform a primary normal-para hydrogen conversion reaction.

[0067] Step 7: After the primary cooling and reaction, the pressure and temperature of the hydrogen are measured by the pressure sensor (6) and the temperature sensor (7), and a portion of the hydrogen enters the gas chromatograph (23) for parahydrogen content detection, and the other portion enters the liquid hydrogen dewar (16) for secondary cooling and reaction.

[0068] Step 8: The hydrogen gas entering the liquid hydrogen dewar (16) passes through the reflux heat exchanger (13) for sufficient heat exchange, and then enters the conversion microchannel (12) in the continuous conversion reactor (14) after the pressure and temperature are measured by the pressure sensor (6) and the temperature sensor (7).

[0069] Step 9: The GM refrigerator (15) provides cooling capacity to the conversion microchannel (12). The hydrogen is cooled for the second time and liquefied. At the same time, due to the action of the ortho-para-hydrogen conversion catalyst (26) carried on the inner wall of the conversion microchannel (12), a secondary ortho-para-hydrogen catalytic conversion occurs.

[0070] Step 10: The liquid hydrogen that has undergone secondary cooling and reaction enters the reflux heat exchanger (13) after the pressure and temperature are measured by the pressure sensor (6) and the temperature sensor (7), and exchanges heat with the incoming hydrogen gas, fully utilizing the cooling capacity of the liquid hydrogen, and then flows out of the liquid hydrogen dewar (16).

[0071] Step 11: A portion of the hydrogen gas coming out of the liquid hydrogen dewar (16) enters the gas chromatograph (23) to detect its parahydrogen content, and the other portion is subjected to temperature measurement using the temperature sensor (7).

[0072] Step 12: The hydrogen gas after temperature measurement is reheated through the reheating pipe (18) and the heating resistor (19), and after the pressure is reduced by the pressure reducing valve (20), enters the flow meter (21) to measure the flow rate.

[0073] Step 13. Finally, the measurement data is recorded and exported, and the hydrogen is vented to the atmosphere.

[0074] Step 14: Close all valves and working equipment. After the test platform stops working and stabilizes, remove the isothermal conversion reactor (11), the continuous conversion reactor (14), and the conversion microchannel (12), replace them with a filled para-hydrogen conversion catalyst (25), and place the para-hydrogen catalytic conversion reactor at a different position in the system, and repeat steps 3 to 13.

[0075] During the primary cooling and reaction process, hydrogen is cooled by liquid nitrogen (10) and then undergoes ortho-para-hydrogen conversion under the action of a wall-mounted ortho-para-hydrogen conversion catalyst (26). The pressure and temperature are measured by a pressure sensor (6) and a temperature sensor (7). The para-hydrogen content in the hydrogen after the reaction is detected by a gas chromatograph (23). The degree of ortho-para-hydrogen catalytic conversion under different temperature and pressure conditions in the gas phase temperature zone is obtained. The changes in temperature, pressure and para-hydrogen content are analyzed. The thermodynamic performance, hydraulic performance and ortho-para-hydrogen conversion performance of the hydrogen liquefaction process under different ortho-para-hydrogen conversion catalyst loading modes are explored, and the coupled flow heat transfer mechanism of ortho-para-hydrogen catalytic conversion in the gas phase temperature zone is revealed.

[0076] During the secondary cooling and reaction process, hydrogen is deeply cooled and converted to ortho-parahydrogen under the cooling capacity provided by the GM refrigerator (15). The pressure and temperature are measured by the pressure sensor (6) and the temperature sensor (7) to obtain the temperature and pressure conditions when the hydrogen is liquefied. The parahydrogen content in the hydrogen after the reaction is detected by a gas chromatograph (23) to obtain the degree of catalytic conversion of ortho-parahydrogen under different temperature and pressure conditions in the liquid phase temperature range. The changes in temperature, pressure and parahydrogen content are analyzed to explore the thermodynamic performance, hydraulic performance and ortho-parahydrogen conversion performance of the hydrogen liquefaction process under different ortho-parahydrogen conversion catalyst loading methods, and to reveal the coupled flow heat transfer mechanism of catalytic conversion of ortho-parahydrogen in the liquid phase temperature range.

[0077] The hydraulic performance, thermal performance and normal-para hydrogen conversion performance of the hydrogen liquefaction process can be described by the following formula:

[0078]

[0079]

[0080] Where ΔP is the pressure drop (Pa); is the fluid density (kg / m 3 ); u is the speed (m / s); L is the length of the microchannel (m); is the parahydrogen content at the microchannel outlet (%); is the mole fraction of parahydrogen after reaching equilibrium; D h is the equivalent diameter (m).

[0081] Among them, the Reynolds number Re calculation formula is:

[0082] Where, u is Speed ​​(m / s); d is the microchannel diameter (m); ν is the kinematic viscosity of the fluid (m 2 / s).

[0083] The expression of the Prandtl number Pr is as follows:

[0084] Where, μ is the dynamic viscosity of the fluid ( Pa · s ); λ is the thermal conductivity of the fluid (W / (m∙K)), c p is the isobaric specific heat capacity of the fluid (J / (kg∙K)).

[0085] The Nusselt number Nu is defined as:

[0086] Where, d is the microchannel diameter, m; h is the heat transfer coefficient, W / (m·k); λ is the thermal conductivity of the fluid, W / (m2·k).

[0087] The present invention is conducive to exploring the flow and heat transfer characteristics of the hydrogen liquefaction process with different para-hydrogen catalyst loading modes, multiple temperature zones, and multiple conversion modes. Based on the interaction mechanism of gas-liquid two-phase flow and mass transfer and heat transfer, the present invention carries out hydrogen liquefaction performance tests in microchannels under different phases and flow rates, studies the influence of catalyst loading mode and para-hydrogen conversion mode on thermal performance and hydraulic performance under multi-phase flow, establishes a gas-liquid two-phase flow and heat and mass transfer coupling model in the microchannel, reveals the flow and heat transfer coupling mechanism under the influence of continuous heat release and catalyst loading mode, and thus optimizes the cooling capacity distribution in the hydrogen liquefaction process.

[0088] The present invention is conducive to exploring the n-para hydrogen conversion behavior in different n-para hydrogen catalyst loading modes, multiple temperature zones, and multiple conversion modes, matching the reaction kinetics of each temperature zone, coupling the microchannel multiphase flow mass transfer and heat transfer model in the gradient cooling process, analyzing the multiphase n-para hydrogen conversion performance, revealing the synergistic influence mechanism of the continuous conversion, flow, and heat transfer of n-para hydrogen, thereby optimizing the hydrogen liquefaction process integrating n-para hydrogen conversion, heat exchange, and liquefaction, and forming a theoretical method to guide the efficient conversion and liquefaction of hydrogen.

[0089] Although the present invention is disclosed as above, the scope of protection disclosed by the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A multifunctional hydrogen liquefaction performance testing platform, characterized in that: Includes the following connected in sequence: Gas supply system: used to provide and purify raw hydrogen; Catalytic reaction and gradient cooling system: used to receive hydrogen from the gas supply system, perform catalytic conversion of normal and para hydrogen, and perform graded cooling and liquefaction of the hydrogen, including: Primary cooling and conversion unit: The hydrogen is pre-cooled using a liquid nitrogen cooling source, and the first normal-para hydrogen conversion reaction is carried out in the primary normal-para hydrogen catalytic conversion reactor; Secondary cooling, liquefaction and conversion unit: used to receive hydrogen from the primary cooling and conversion unit, deeply cool the hydrogen to liquefaction using the cold source provided by the GM refrigerator, and simultaneously carry out secondary normal-para-hydrogen conversion reaction in the secondary normal-para-hydrogen catalytic conversion reactor; Rewarming and measurement system: Receives hydrogen gas / liquid hydrogen flow from the secondary cooling liquefaction and conversion unit, including: Reheating unit: used to reheat low-temperature hydrogen; Data measurement unit: used to measure temperature, pressure, flow rate and parahydrogen content parameters during the hydrogen liquefaction process.

2. The multifunctional hydrogen liquefaction performance testing platform according to claim 1, characterized in that: The test platform also includes: The catalyst loading system comprises a detachable conversion microchannel (12), wherein the conversion microchannel (12) is arranged inside the first-stage normal-parahydrogen catalytic conversion reactor and the second-stage normal-parahydrogen catalytic conversion reactor, and is used to load a filled normal-parahydrogen conversion catalyst (25) or a wall-mounted normal-parahydrogen conversion catalyst (26); The first-stage normal-parahydrogen catalytic conversion reactor and the second-stage normal-parahydrogen catalytic conversion reactor adopt a detachable isothermal conversion reactor (11), an adiabatic conversion reactor (24) or a continuous conversion reactor (14).

3. The multifunctional hydrogen liquefaction performance testing platform according to claim 1, characterized in that: In the catalyst loading system: The filled normal-parahydrogen conversion catalyst (25) is filled in the inner space of the conversion microchannel (12); The wall-supported normal-parahydrogen conversion catalyst (26) is supported on the inner wall surface of the conversion microchannel (12).

4. The multifunctional hydrogen liquefaction performance testing platform according to claim 1, characterized in that: The secondary cooling liquefaction and conversion unit includes a liquid hydrogen dewar (16) with a double-layer cold preservation structure, wherein the double-layer cold preservation structure consists of an inner liquid nitrogen cold shield structure and an outer vacuum sandwich structure, and is used to store liquid hydrogen and reduce heat leakage.

5. The multifunctional hydrogen liquefaction performance testing platform according to claim 4, characterized in that: The secondary cooling liquefaction and conversion unit further comprises a reflux heat exchanger (13) located at the inlet of the liquid hydrogen dewar (16), which is used for heat exchange between the incoming hydrogen and the outgoing low-temperature hydrogen / liquid hydrogen.

6. The multifunctional hydrogen liquefaction performance testing platform according to claim 1, characterized in that: The test platform also includes: Control system: used to connect and regulate valves and pressures in the gas supply system, catalytic reaction and cooling system, rewarming and measurement system; The control system comprises a regulating valve (4), a pressure reducing valve (20) and a venting pipeline; the pressure reducing valve (20) is arranged on the hydrogen final outlet pipeline for reducing the hydrogen pressure; a flow meter (21) and a regulating valve (4) are provided on the venting pipeline; the flow meter (21) is connected to the pressure reducing valve (20).

7. The multifunctional hydrogen liquefaction performance testing platform according to claim 1, characterized in that: The gas supply system comprises a hydrogen gas cylinder (3), a helium gas cylinder (2) and a molecular sieve container (5); the hydrogen gas cylinder (3) and the helium gas cylinder (2) are connected to the molecular sieve container (5), and a regulating valve (4) is provided at the outlet of each of the hydrogen gas cylinder (3) and the helium gas cylinder (2).

8. The multifunctional hydrogen liquefaction performance testing platform according to claim 1, characterized in that: The primary cooling and conversion unit comprises a liquid nitrogen dewar (8) containing liquid nitrogen (10) and a precooling pipeline (9); the precooling pipeline (9) is immersed in the liquid nitrogen (10), constituting a primary cooling place for hydrogen; the primary normal-parahydrogen catalytic conversion reactor is arranged downstream of the primary cooling place or integrated therein.

9. The multifunctional hydrogen liquefaction performance testing platform according to claim 2, characterized in that: In the secondary cooling liquefaction and conversion unit, the continuous conversion reactor (14) is in direct thermal contact with the cold head of the GM refrigerator (15).

10. A test method using the multifunctional hydrogen liquefaction performance test platform according to any one of claims 1 to 9, characterized in that: include: S1: Loading the activated normal-parahydrogen conversion catalyst into the conversion microchannel (12), selecting a wall-loaded or filled-type loading structure; S2: selecting any one or more types of normal-parahydrogen catalytic conversion reactors from an isothermal conversion reactor (11), an adiabatic conversion reactor (24), and a continuous conversion reactor (14), and placing the catalytic conversion reactor at a selected position of the gradient cooling system; S3: hydrogen is introduced, and primary cooling and conversion, secondary cooling, liquefaction and conversion are performed in sequence; S4: Record and analyze the temperature, pressure, flow rate and parahydrogen content parameters during the hydrogen liquefaction process based on the data measurement unit; S5: changing at least one of the catalyst loading method, the reactor type, or the reactor position, and repeating steps S3-S4.

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